On Wed, Mar 07, 2001 at 09:15:36PM +0100, Jens Axboe wrote:> On Wed, Mar 07 2001, Stephen C. Tweedie wrote:> > > > For most fs'es, that's not an issue. The fs won't start writeback on> > the primary disk at all until the journal commit has been acknowledged> > as firm on disk.> > But do you then force wait on that journal commit?

It doesn't matter too much --- it's only the writeback which is doingthis (ext3 uses a separate journal thread for it), so any sleep isonly there to wait for the moment when writeback can safely begin:users of the filesystem won't see any stalls.

> A barrier operation is sufficient then. So you're saying don't> over design, a simple barrier is all you need?

Pretty much so. The simple barrier is the only thing which can beeffectively optimised at the hardware level with SCSI anyway.